Wireless local area network (WLAN) systems enable the communication of data via a wireless communication medium by, for example, transmitting radio frequency (RF) signals that carry data between a transmitting station and a receiving station. A range of frequencies, referred to as the WLAN frequency spectrum, may be utilized for communication between stations in a WLAN system. The frequency spectrum may be divided into RF channels wherein each RF channel represented an assigned frequency within the WLAN frequency spectrum. Each RF channel may, in turn, comprise a range of frequencies referred to as an RF channel bandwidth. Each RF channel within the WLAN frequency spectrum may comprise a range of frequencies, which is non-overlapping and distinct from other RF channels.
Smart antenna systems may be utilized in WLAN systems to enable the transmission and/or reception of signals via a wireless communication medium. A smart antenna system may refer to a system, which may dynamically configure its directivity pattern. For a smart antenna system located at a transmitting station, most of the signal energy may be radiated in a particular direction. The desired transmission directivity pattern may be configured at a transmitting station based on the location of the receiving station. For example, the desired transmission directivity pattern may be selected to maximize the amount of signal energy transmitted by the transmitting station, which is received at the receiving station.
For a smart antenna system located at a receiving station, an antenna directivity pattern may be configured to coincide with the angle of arrival (AOA) of the received signals.
Antenna directionality is expressed in dBi (Decibel Isotropic) which is a measurement of focus that an antenna has compared to a mathematically ideal isotropic antenna which has a uniform focus in all directions.
Smart antenna systems may contain a plurality of highly directional antenna elements, wherein each antenna element may be oriented in a particular direction. In such highly directional antenna systems, the smart antenna system may enable selection of antenna elements to achieve a desired transmission directivity pattern. Such systems may be referred to as switched beam smart antenna systems. Smart antenna systems may also contain a plurality of omnidirectional antenna elements, wherein the antenna directivity pattern may be oriented, or steered, in various directions by adjusting the phase of the signal applied to each antenna element. Such systems may be referred to as adaptive array smart antenna systems.
Antenna directivity pattern in a smart antenna system may be selected based on received signal strength indication (RSSI) measurements taken from received signals and/or by analyzing the rate at which acknowledgments from previously transmitted protocol data units (PDU) are received. The acknowledgments may provide an indication to the transmitting station that previously transmitted PDUs were successfully received by the receiving station.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.